Memory devices such as NAND flash non-volatile memory devices are particularly vulnerable to errors in the data being read from the memory cells. A measure of the rate of errors, known as the Bit Error Rate (BER), is an important quantity which determines error detection and correction schemes and other data integrity functions. Another important measure is the Frame Error Rate (FER), which is the rate of errors in decoded frames of data from the error correction scheme. However, the determination of the FER is a time consuming task, where typical error rates of the order of one in a million or even less can involve millions of write and read test operations in order to arrive at an accurate FER estimation.